<?php

/*
 * This file is part of Composer.
 *
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Composer\DependencyResolver;

use Composer\Repository\RepositoryInterface;
use Composer\Package\PackageInterface;
use Composer\Package\AliasPackage;
use Composer\DependencyResolver\Operation;

/**
 * @author Nils Adermann <naderman@naderman.de>
 */
class RuleSetGenerator
{
    protected $policy;
    protected $pool;
    protected $rules;
    protected $jobs;
    protected $installedMap;

    public function __construct(PolicyInterface $policy, Pool $pool)
    {
        $this->policy = $policy;
        $this->pool = $pool;
    }

    /**
     * Creates a new rule for the requirements of a package
     *
     * This rule is of the form (-A|B|C), where B and C are the providers of
     * one requirement of the package A.
     *
     * @param PackageInterface $package    The package with a requirement
     * @param array            $providers  The providers of the requirement
     * @param int              $reason     A RULE_* constant describing the
     *                                     reason for generating this rule
     * @param mixed            $reasonData Any data, e.g. the requirement name,
     *                                     that goes with the reason
     * @return Rule                        The generated rule or null if tautological
     */
    protected function createRequireRule(PackageInterface $package, array $providers, $reason, $reasonData = null)
    {
        $literals = array(new Literal($package, false));

        foreach ($providers as $provider) {
            // self fulfilling rule?
            if ($provider === $package) {
                return null;
            }
            $literals[] = new Literal($provider, true);
        }

        return new Rule($literals, $reason, $reasonData);
    }

    /**
     * Creates a new rule for installing a package
     *
     * The rule is simply (A) for a package A to be installed.
     *
     * @param PackageInterface $package    The package to be installed
     * @param int              $reason     A RULE_* constant describing the
     *                                     reason for generating this rule
     * @param mixed            $reasonData Any data, e.g. the package name, that
     *                                     goes with the reason
     * @return Rule                        The generated rule
     */
    protected function createInstallRule(PackageInterface $package, $reason, $reasonData = null)
    {
        return new Rule(new Literal($package, true));
    }

    /**
     * Creates a rule to install at least one of a set of packages
     *
     * The rule is (A|B|C) with A, B and C different packages. If the given
     * set of packages is empty an impossible rule is generated.
     *
     * @param array   $packages   The set of packages to choose from
     * @param int     $reason     A RULE_* constant describing the reason for
     *                            generating this rule
     * @param array   $job        The job this rule was created from
     * @return Rule               The generated rule
     */
    protected function createInstallOneOfRule(array $packages, $reason, $job)
    {
        $literals = array();
        foreach ($packages as $package) {
            $literals[] = new Literal($package, true);
        }

        return new Rule($literals, $reason, $job['packageName'], $job);
    }

    /**
     * Creates a rule to remove a package
     *
     * The rule for a package A is (-A).
     *
     * @param PackageInterface $package    The package to be removed
     * @param int              $reason     A RULE_* constant describing the
     *                                     reason for generating this rule
     * @param array            $job        The job this rule was created from
     * @return Rule                        The generated rule
     */
    protected function createRemoveRule(PackageInterface $package, $reason, $job)
    {
        return new Rule(array(new Literal($package, false)), $reason, $job['packageName'], $job);
    }

    /**
     * Creates a rule for two conflicting packages
     *
     * The rule for conflicting packages A and B is (-A|-B). A is called the issuer
     * and B the provider.
     *
     * @param PackageInterface $issuer     The package declaring the conflict
     * @param Package          $provider   The package causing the conflict
     * @param int              $reason     A RULE_* constant describing the
     *                                     reason for generating this rule
     * @param mixed            $reasonData Any data, e.g. the package name, that
     *                                     goes with the reason
     * @return Rule                        The generated rule
     */
    protected function createConflictRule(PackageInterface $issuer, PackageInterface $provider, $reason, $reasonData = null)
    {
        // ignore self conflict
        if ($issuer === $provider) {
            return null;
        }

        return new Rule(array(new Literal($issuer, false), new Literal($provider, false)), $reason, $reasonData);
    }

    /**
     * Adds a rule unless it duplicates an existing one of any type
     *
     * To be able to directly pass in the result of one of the rule creation
     * methods.
     *
     * @param int  $type    A TYPE_* constant defining the rule type
     * @param Rule $newRule The rule about to be added
     */
    private function addRule($type, Rule $newRule = null) {
        if ($this->rules->containsEqual($newRule)) {
            return;
        }

        $this->rules->add($newRule, $type);
    }

    protected function addRulesForPackage(PackageInterface $package)
    {
        $workQueue = new \SplQueue;
        $workQueue->enqueue($package);

        while (!$workQueue->isEmpty()) {
            $package = $workQueue->dequeue();
            if (isset($this->addedMap[$package->getId()])) {
                continue;
            }

            $this->addedMap[$package->getId()] = true;

            foreach ($package->getRequires() as $link) {
                $possibleRequires = $this->pool->whatProvides($link->getTarget(), $link->getConstraint());

                $this->addRule(RuleSet::TYPE_PACKAGE, $rule = $this->createRequireRule($package, $possibleRequires, Rule::RULE_PACKAGE_REQUIRES, (string) $link));

                foreach ($possibleRequires as $require) {
                    $workQueue->enqueue($require);
                }
            }

            foreach ($package->getConflicts() as $link) {
                $possibleConflicts = $this->pool->whatProvides($link->getTarget(), $link->getConstraint());

                foreach ($possibleConflicts as $conflict) {
                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createConflictRule($package, $conflict, Rule::RULE_PACKAGE_CONFLICT, (string) $link));
                }
            }

            // check obsoletes and implicit obsoletes of a package
            $isInstalled = (isset($this->installedMap[$package->getId()]));

            foreach ($package->getReplaces() as $link) {
                $obsoleteProviders = $this->pool->whatProvides($link->getTarget(), $link->getConstraint());

                foreach ($obsoleteProviders as $provider) {
                    if ($provider === $package) {
                        continue;
                    }

                    if (!$this->obsoleteImpossibleForAlias($package, $provider)) {
                        $reason = ($isInstalled) ? Rule::RULE_INSTALLED_PACKAGE_OBSOLETES : Rule::RULE_PACKAGE_OBSOLETES;
                        $this->addRule(RuleSet::TYPE_PACKAGE, $this->createConflictRule($package, $provider, $reason, (string) $link));
                    }
                }
            }

            // check implicit obsoletes
            // for installed packages we only need to check installed/installed problems,
            // as the others are picked up when looking at the uninstalled package.
            if (!$isInstalled) {
                $obsoleteProviders = $this->pool->whatProvides($package->getName(), null);

                foreach ($obsoleteProviders as $provider) {
                    if ($provider === $package) {
                        continue;
                    }

                    if (($package instanceof AliasPackage) && $package->getAliasOf() === $provider) {
                        $this->addRule(RuleSet::TYPE_PACKAGE, $rule = $this->createRequireRule($package, array($provider), Rule::RULE_PACKAGE_ALIAS, (string) $package));
                    } else if (!$this->obsoleteImpossibleForAlias($package, $provider)) {
                        $reason = ($package->getName() == $provider->getName()) ? Rule::RULE_PACKAGE_SAME_NAME : Rule::RULE_PACKAGE_IMPLICIT_OBSOLETES;
                        $this->addRule(RuleSet::TYPE_PACKAGE, $rule = $this->createConflictRule($package, $provider, $reason, (string) $package));
                    }
                }
            }
        }
    }

    protected function obsoleteImpossibleForAlias($package, $provider)
    {
        $packageIsAlias = $package instanceof AliasPackage;
        $providerIsAlias = $provider instanceof AliasPackage;

        $impossible = (
            ($packageIsAlias && $package->getAliasOf() === $provider) ||
            ($providerIsAlias && $provider->getAliasOf() === $package) ||
            ($packageIsAlias && $providerIsAlias && $provider->getAliasOf() === $package->getAliasOf())
        );

        return $impossible;
    }

    /**
     * Adds all rules for all update packages of a given package
     *
     * @param PackageInterface $package  Rules for this package's updates are to
     *                                   be added
     * @param bool             $allowAll Whether downgrades are allowed
     */
    private function addRulesForUpdatePackages(PackageInterface $package)
    {
        $updates = $this->policy->findUpdatePackages($this->pool, $this->installedMap, $package);

        foreach ($updates as $update) {
            $this->addRulesForPackage($update);
        }
    }

    protected function addRulesForJobs()
    {
        foreach ($this->jobs as $job) {
            switch ($job['cmd']) {
                case 'install':
                    if ($job['packages']) {
                        foreach ($job['packages'] as $package) {
                            if (!isset($this->installedMap[$package->getId()])) {
                                $this->addRulesForPackage($package);
                            }
                        }

                        $rule = $this->createInstallOneOfRule($job['packages'], Rule::RULE_JOB_INSTALL, $job);
                        $this->addRule(RuleSet::TYPE_JOB, $rule);
                    }
                break;
                case 'remove':
                    // remove all packages with this name including uninstalled
                    // ones to make sure none of them are picked as replacements
                    foreach ($job['packages'] as $package) {
                        $rule = $this->createRemoveRule($package, Rule::RULE_JOB_REMOVE, $job);
                        $this->addRule(RuleSet::TYPE_JOB, $rule);
                    }
                break;
            }
        }
    }

    public function getRulesFor($jobs, $installedMap)
    {
        $this->jobs = $jobs;
        $this->rules = new RuleSet;
        $this->installedMap = $installedMap;

        foreach ($this->installedMap as $package) {
            $this->addRulesForPackage($package);
            $this->addRulesForUpdatePackages($package);
        }

        $this->addRulesForJobs();

        return $this->rules;
    }
}